Abstract

Lg-wave synthetic seismograms are presented in order to analyze the influence of anisotropy in the continental crust on their three-component waveforms. The effect of dry and liquid-filled open cracks in the upper crust and petrological anisotropy in the lower crust on waves produced by surface explosions and crustal earthquakes is examined. The polarization, and especially the amplitude of the transverse component, proves to be very sensitive to introduction of weak anisotropy in the crust. Comparisons of the modeling with Lg-wave data produced by explosions in southern Scandinavia show that a realistic crustal anisotropy can explain observations that the transverse components of these waves are as large as their vertical ones. A 10-km-thick surficial layer with liquid-filled open cracks is our perferred model for southern Scandinavia.

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